Think what you like. I’m a competitive athlete and have been for decades, including swimming. I have seen plenty of good black runners, both sprinters and long distance, fast and slow twitch. Never seen a black swimmer that is even close to being good. A 100 metre runner has no chance against a good swimmer in a short course swimming race despite being built to go flat out.
Understand the physics of buoyancy and the composition of different body masses and there lies the answer.
